1. Field of the Invention
The present invention relates to an image processing apparatus capable of handling paper-fingerprint information, a method for controlling the image processing apparatus, a program, and a storage medium.
2. Description of the Related Art
Documents for which the security of the original is important include public documents such as certificate of residence, certificate of insurance, and other confidential documents. With the advancement of printing technology, such paper documents can be printed using image forming apparatuses such as printers and copying machines, and protection against forgery using color scanners or color copying machines has been demanded.
One available technique for protection against forgery using color scanners or color copying machines is to embed a pattern, such as a copy-forgery-inhibited pattern, in paper to be printed such that when the paper is copied, the embedded copy-forgery-inhibited pattern becomes visible. Another technique is available to attach to paper a semiconductor component having data for authenticating the original, such as a contactless integrated circuit (IC) or radio-frequency identification (RFID) chip, so that a scanner or a copying machine, when copying the paper, can record information read from the semiconductor component to provide a record of copying. It has also been proposed to combine such a technique and a user authentication technique so that copying by a copying machine can be prohibited unless user authentication based on the information read from the semiconductor component is performed.
Further, it has also been proposed to embed specific halftone pattern information illegible to users as invisible information when a document is printed so that the printing operation can be terminated if a scanner or copying machine reads the information when copying the document.
However, the attachment of such a semiconductor component to paper causes an increase in the cost of the paper. There is another problem in that the scanner or copying machine may require special hardware to attach or read the invisible information or to support the above-described contactless IC or RFID chip, resulting in increased cost.
To addresses such problems, as disclosed in Japanese Patent Laid-Open No. 2004-112644, there has been recently proposed a technique utilizing a difference in the arrangement of fibers on a surface of a recording medium such as paper from one sheet of paper to another. In this technique, a surface of a recording medium such as paper is read using a reader of a scanner or a copying machine, and the read surface information such as the arrangement of fibers (generally referred to as “paper fingerprint” or the like) is converted as pattern data into digital information for recording. In the recording process, for example, the digital information is printed as a halftone pattern on a sheet of paper.
In the technique described above, when a recording medium such as paper once printed is then read for copying, information concerning the fiber pattern of the paper and digital information into which pattern data printed on the paper has been converted are compared to verify the authenticity of the original. This technique allows the authenticity of the original to be verified at low cost using existing scanners, printers, or copying machines only by modifying a portion of the software.
However, paper-fingerprint information (digital data into which a paper fingerprint read from paper has been converted) is registered by, first, scanning a sheet of printing paper (blank) for which the paper-fingerprint information is to be registered and reading the paper fingerprint. Further, the scanned sheet is placed on a print tray, and the read paper-fingerprint information is attached as a halftone pattern or the like to the sheet placed on the print tray. Therefore, a time-consuming operation is required to register the paper fingerprint. Further, when the read paper fingerprint is attached to the sheet, it may be necessary to correctly adjust the orientation, side, etc., of the sheet.